Air is a physical substance which has weight. It has molecules which are constantly moving. Air pressure is created by the molecules moving around. Moving air has a force that will lift kites and balloons up and down. Air is a mixture of different gases; oxygen, carbon dioxide and nitrogen. All things that fly need air. Air has power to push and pull on the birds, balloons, kites and planes. In 1640, Evangelista Torricelli discovered that air has weight. When experimenting with measuring mercury, he discovered that air put pressure on the mercury.

Francesco Lana used this discovery to begin to plan for an airship in the late 1600s. He drew an airship on paper that used the idea that air has weight. The ship was a hollow sphere which would have the air taken out of it. Once the air was removed, the sphere would have less weight and would be able to float up into the air. Each of four spheres would be attached to a boat-like structure and then the whole machine would float. The actual design was never tried.

Hot air expands and spreads out and it becomes lighter than cool air. When a balloon is full of hot air it rises up because the hot air expands inside the balloon. When the hot air cools and is let out of the balloon the balloon comes back down.

How Wings Lift the Plane

Airplane wings are curved on the top which make air move faster over the top of the wing. The air moves faster over the top of a wing. It moves slower underneath the wing. The slow air pushes up from below while the faster air pushes down from the top. This forces the wing to lift up into the air.

Laws of Motion

Sir Isaac Newton proposed three laws of motion in 1665. These Laws of Motion help to explain how a planes flies.

If an object is not moving, it will not start moving by itself. If an object is moving, it will not stop or change direction unless something pushes it.

Objects will move farther and faster when they are pushed harder.

When an object is pushed in one direction, there is always a resistance of the same size in the opposite direction.

Forces of Flight

Four Forces of Flight

Lift - upward

Drag - down and backward

Weight - downward

Thrust - forward

Controlling the Flight of a Plane

How does a plane fly? Let's pretend that our arms are wings. If we place one wing down and one wing up we can use the roll to change the direction of the plane. We are helping to turn the plane by yawing toward one side. If we raise our nose, like a pilot can raise the nose of the plane, we are raising the pitch of the plane. All these dimensions together combine to control the flight of the plane. A pilot of a plane has special controls that can be used to fly the plane. There are levers and buttons that the pilot can push to change the yaw, pitch and roll of the plane.

To roll the plane to the right or left, the ailerons are raised on one wing and lowered on the other. The wing with the lowered aileron rises while the wing with the raised aileron drops.

Pitch is to make a plane descend or climb. The pilot adjusts the elevators on the tail to make a plane descend or climb. Lowering the elevators caused the airplane's nose to drop, sending the plane into a down. Raising the elevators causes the airplane to climb.

Yaw is the turning of a plane. When the rudder is turned to one side, the airplane moves left or right. The airplane's nose is pointed in the same direction as the direction of the rudder. The rudder and the ailerons are used together to make a turn

How does a Pilot Control the Plane?

To control a plane a pilot uses several instruments...

The pilot controls the engine power using the throttle. Pushing the throttle increases power, and pulling it decreases power.

Left: Picture of plane in roll

The ailerons raise and lower the wings. The pilot controls the roll of the plane by raising one aileron or the other with a control wheel. Turning the control wheel clockwise raises the right aileron and lowers the left aileron, which rolls the aircraft to the right.

Right: Picture of plane Yaw

The rudder works to control the yaw of the plane. The pilot moves rudder left and right, with left and right pedals. Pressing the right rudder pedal moves the rudder to the right. This yaws the aircraft to the right. Used together, the rudder and the ailerons are used to turn the plane.

Left: Picture of Plane Pitch

The elevators which are on the tail section are used to control the pitch of the plane. A pilot uses a control wheel to raise and lower the elevators, by moving it forward to back ward. Lowering the elevators makes the plane nose go down and allows the plane to go down. By raising the elevators the pilot can make the plane go up.

The pilot of the plane pushes the top of the rudder pedals to use thebrakes. The brakes are used when the plane is on the ground to slow down the plane and get ready for stopping it. The top of the left rudder controls the left brake and the top of the right pedal controls the right brake.

If you look at these motions you can see that each type of motion helps control the direction and level of the plane when it is flying.

Sound Barrier

Sound is made up of molecules of air that move. They push together and gather together to form sound waves . Sound waves travel at the speed of about 750 mph at sea level. When a plane travels the speed of sound the air waves gather together and compress the air in front of the plane to keep it from moving forward. This compression causes a shock wave to form in front of the plane.

In order to travel faster than the speed of sound the plane needs to be able to break through the shock wave. When the airplane moves through the waves, it is makes the sound waves spread out and this creates a loud noise or sonic boom. The sonic boom is caused by a sudden change in the air pressure. When the plane travels faster than sound it is traveling at supersonic speed. A plane traveling at the speed of sound is traveling at Mach 1or about 760 MPH. Mach 2 is twice the speed of sound.

Regimes of Flight

Sometimes called speeds of flight, each regime is a different level of flight speed.

Example

Regimes of Flight

Seaplane

General Aviation(100-350 MPH).

Most of the early planes were only able to fly at this speed level. Early engines were not as powerful as they are today. However, this regime is still used today by smaller planes. Examples of this regime are the small crop dusters used by farmers for their fields, two and four seater passenger planes, and seaplanes that can land on water.

Boeing 747

Subsonic (350-750 MPH).

This category contains most of the commercial jets that are used today to move passengers and cargo. The speed is just below the speed of sound. Engines today are lighter and more powerful and can travel quickly with large loads of people or goods.

Concorde

Supersonic (760-3500 MPH - Mach 1 - Mach 5).

760 MPH is the speed of sound. It is also called MACH 1. These planes can fly up to 5 times the speed of sound. Planes in this regime have specially designed high performance engines. They are also designed with lightweight materials to provide less drag. The Concorde is an example of this regime of flight.

Space Shuttle

Hypersonic (3500-7000 MPH - Mach 5 to Mach 10).

Rockets travel at speeds 5 to 10 times the speed of sound as they go into orbit. An example of a hypersonic vehicle is the X-15, which is rocket powered. The space shuttle is also an example of this regime. New materials and very powerful engines were developed to handle this rate of speed.

A. Trouble shooting is the systematic process of identifying the faulty element in an otherwise functional system and determining the actions necessary to restore the system to an operational condition.

B. Trouble shooting begins with recognition and documentation of the problem. Precise documentation is essential to isolation of the fault with a minimum expenditure of time and effort.

C. 737-300 Power Plant Trouble Shooting includes lists of common trouble symptoms and related trouble shooting procedures. Trouble shooting procedures are in the form of charts which include trouble shooting steps and corrective actions in a recommended sequence based on probability of component failure and how easy it is to do the necessary checks.

D. Trouble shooting procedures are based on the assumptions that follow:

(1) Double failures do not exist.

(2) The faulty system was fully operational before the fault indication with all equipment installed correctly.

(5) The airplane is on the ground, it has been shut down in accordance with normal operating procedures and all power is off.

(6) Fault was accurately described.

E. All warnings, cautions and operating limitations related with power plant maintenance and operation must be used during trouble shooting.

F. Generally, electrical wiring is considered to be satisfactory. The location of the wiring, its environment, exposure to possible damage and experienced failure rate will be factors in determining the need for electrical circuit checks.

G. All electrical wiring and connectors must be correctly examined and installed with the standard practices (AMM 70-70-01/201).

2. Trouble Shooting Arrangement

A. Power Plant trouble shooting is separated into the major sections that follow:

Starting and Idle AMM 71-00-41/101

Power and Engine Response AMM 71-00-42/101

Surge (Stall) AMM 71-00-43/101

Oil System AMM 71-00-44/101

Fuel System AMM 71-00-46/101

Misc Observed Problems (Vibration, FOD, etc.) AMM 71-00-47/101

Engine Controls AMM 71-00-49/101

Thrust Reverser AMM 71-00-50/101

Fuel Indicating AMM 71-00-53/101

Engine Indicating AMM 71-00-54/101

Oil Indicating AMM 71-00-55/101

Visual Checks AMM 71-00-58/101

Engine Checks AMM 71-00-59/101

B. Each section includes a listing of trouble symptoms related with the section. Each listed symptom includes a reference to the trouble shooting chart (figure) and block sn the chart to start trouble shooting for the particular problem.

C. Trouble shooting charts are given for major symptoms. Each chart is given a figure number. Component location illustrations and schematic diagrams are given where necessary to support trouble shooting.

(1) Prerequisites are given to make sure that the system is in the necessary mode, and include the power necessary and identification of the circuit breakers which need to be closed ("in"), to do the procedure. Time consuming operations such as engine operation are noted.

Circuit breaker locations are defined as follows.

EXAMPLE: 6-3-B13 P6-3 Panel, Grid Location B13

D. Visual checks (AMM 71-00-58/101) and Engine checks (AMM 71-00-59/101) sections given details for checks that show repeatedly in trouble shooting charts or that have a degree of complexity requiring a detailed procedure or specific illustrations. Visual checks are those checks which are done by visual observation only (opening of fan cowls or fan duct cowl and thrust reverser halves for access may be necessary). Engine checks are more complex and may require test equipment, engine operation, or removal of components.

E. Trouble shooting tips may be included in the section introduction to describe typical problems to the mechanic or technician, and to alert of specific pitfalls that can occur. F. Tests are given in section AMM 71-00-00/501 that may be referred to by the trouble-shooting charts, or as is necessary to follow maintenance activity. Test No. 12 in section AMM 71-00-00/501 is intended to be used as a diagnostic aid. Test No. 12 includes an engine run data sheet for use to record engine parameters to determine any necessary adjustments or component replacement. The engine data for the Idle Speed, Acceleration, Part Power, and MPA tests in Test No. 12 can be collected in one continuous engine run before analysis. Or, the analysis and related corrective actions can be done after each power level check.